Radio apparatus for intercommunication or duplex operation



M30, 1932. K. HEFFNER 1,874 993 RADIO APPARATUS FOR INTERCOMMUNICATION OR DUPLEX OPERATION Filed April 24, 1929 INVENTOR KARL HEFFNE ATTORNEY Patented Aug. 30, 1932 ED STATES PATENT ()FFECE KARL HEIFFNER, OF BERLIN, GERMANY, ASSIGNOR TO TELEFUNKEN GESELLSCHAFT EUR DRAI-ITLOSE TELEGRAPHIE M. B. H., BERLIN, GERMANY, A CORPORATION OF GERMANY.

I RADIO APPARATU S FOR INTERGOMMUNICATIQN R DUIPLEX OPERATION Application filed April 24, 1929, Serial No. 357,635, and in Germany May 5, 1928.

In a radiostation intended for duplex operation, the circuits of the receiver and the transmitter are independent of each other. This is necessary since means must be provided so that each of the two apparatus must be capable of being rendered operative, separately and individually, or simultaneously. In the case of a station designed for intercommunication, however, some of the circuits at the transmitter and the receiver are interdependent. For instance, while receiving signals the filament current at the transmitter should be disconnected for the sake of economy. Conversely, while transmitting signals, the filament current of the receiver tubes should be broken. Another point is that, if a common antenna be used, the latter must be connected alternately with the transmitter and the receiver. To accomplish this changeover there is used as a rule what is known as a combination transmitter and receiver switch. This switch may be in practice either an integral constructional part of the transmitter or a separate part.

to operate occasionally on the duplex principle and other timeson the intercommunication principle. This may be accomplished by providing a separate switch in the receiver by means of which those receiving circuits are closed which would otherwise be interrupted when the sending receiving switch connected with the transmitter is moved into a position permitting independent receiver operation. This switch, provided as indicated above, eliminates or obviates the dependence of the receiver upon the position of the said sending receiving switch and permits duplex operation by the same apparatus which is used for intercommunication.

Whenever it is desiredand this happens quite frequently in practicethat the receiver should be more or the transmitter when changing from intercommunication operation to duplexpperation, the means establishing connection between the said sending-receiving switch and the receiver may be made disengageable preferably by means of plugs adapted to be Now, 't may happen that a given station is p y less separated from inserted in and withdrawn from the corresponding receiver connection sockets.

In this instance, when changing over to duplex operation, it will be necessary to eflect two switch motions, i. e., the withdrawal of the plug between sender and receiver, and the closing by the said separate switch of the receiving circuits which are dependent, in intercommunication, upon the position of the sending-receiving switch.

According to the present invention, this circuit change can be accomplished by the aid of a single switch handle manipulation, if arrangements are so made that the act whereby dependence of the receiving circuits upon the sending-receiving switch is caused, is not effected by the agency of a distinct switch to be closed separately, but by that this is effected by the separation of the said connections between said sending-receiving switch and the receiver. In this manner, the change to duplex operation is insured in a wholly automatic manner without the risk or" errors, merely by the always necessary h sical separation'of the receiver by the withdrawal of the plug. Another advantage is that a separate switch to accomplish this operation is unnecessary.

One embodiment of the basic idea of the invention is illustrated by the single figure in the accompanying drawing.

Referring to the drawing,

Of the transmitter T and the receiver R, all circuits not involved in the present invention are omitted. Only the filament circuits of the transmitter and receiver and the plate circuit of the transmitter associated with the sending-receiving switches d, 5, 6 are illustrated. In intercommunication, the antenna A is used both for sending and receiving, and

in duplex traliic the antenna A is only used for sending. Antenna A is used for receiving in duplex operation.

A number of flexible leads or cords 1, 2, 3 for intercommunication trafiic serve to connect the contacts 5, 6 of the sending-receiving switch S, respectively, with the socket contacts 11, 12 and 13 of those circuits of the receiver apparatus which, in intercommunication traffic, must be dependent upon the receiver tube R is closed by Way vention,

tacts 14, 15, and 16 are closed as indicated" by the solid lines, whereby antenna A is connected by way ofswitcli parts 6 and 16, lead 3, plug contact 10, and contact socket 13 with the antenna circuit of the receiver which include, as shown, the antenna load coil 17, coupler coil 18 and ground Gr. ;,'By

the same operation the-filament circuitoi 0 socket 12,plug 9, lead 2, contact 1 5,'switch part 5, lead 1, plug 8, socket 11, and battery 19 to-12.- The filament circuit which includes battery 20, of the transmitter tube broken. v

In this arrangement the receiver R is operative since the filament circuit is energized" and signals received on the antenna'A are impressed therefrom the inductance 18 to the input circuit inductance I,connected between the input electrodes of the tube R and repeated intube R vto-appear in the output circuit connected, as shown, between the anode-and cathode of R -When throwing the sending-receiving switch S to the left for transmitting into a position at whichcontacts'21, 22 and 23 are closed as indicated by the dotted line, the antenna A is inserted in the transmitter antenna circuit through the antenna load coil 24, coupler coil 25, and ground Gr, while the filament circuit of the transmitter is closed by switch part4 and the receiver filament circuit is interrupted by switch 5.

In this position of the switch S the receiver is inoperative since the filament circuit is interrupted. The transmitter is operativesince the filament circuit of the tube therein is closed. The signal generated or repeated in tube 'I appears in the anode circuit thereof and is impressed therefrom by inductance IT to the inductance 25 in the antennacircuit. 1

V Now, in order that the change to duplexing may be accomplished, according to this inonly by the removal of the plug connection 7, instead of by switches separatelyito be actuated, two normally closed contact springs 26 and 27 are provided in the receiving circuits in question. Contact 26 :is in the filament circuit. the circuit of antenna A. When plug device 7 is introduced, the contacts 26 and 27 are pressed away by suitablemeans, as, for exam- Contact 7 27 is in 1 switch ple, by the aid of lugs 30 secured at the ends of the plugs 8 and 10 as indicated by the blackened portions made vfrom insulatingmaterial, from the coacting contacts- 11 and 12, while they Will allow of theautomati'c closure of these contacts when Withdrawing the connector 7 In this manner, duplexing is madefeasible automatically by the mere removal of the connector plug 7'. Of course,

when the plug 7 is removed the receiver R is isolated from the transmitter T. The re ceiver filament circuit and antenna circuit are closed by the contacts 26 and 27 automatically so that signals maybe received. The filament circuit and the antenna circuit of the transmitter are closed by the switch S. The apparatus may be used for intercominunication. A 3 V V I The arrangement as hereinbefore disclosed is suited especially for transportable radio equipments of the kind used, e. g., for military purposes. I V

Having now fully disclosed my invention 7 and its mode of operation, I claim:

1. In radio apparatus for duplex operation the combination of radio receiving apparatus including a thermionic tube having a cathode normally .in circuit with a heating source, and an aerial system normally closed, a radio-transmitter including a thermionic tube and an aerial system, and :means for adapting said apparatus forintercommunication including a plug connection terminating in contacts in the radio transmitter circuits at theone end and being adaptedzto be plugged-into the radio receiverat the other 'eiid,'said plug including means operative when plugged'in to the receiver to in; terrupt the receiver antenna circuitand to completethe heating circuit of the thermionic tube in said receiver. o

2. In combination a radio receiver having an antenna circuit including a biased switch normally closed and a thermionic tube having a heating circuit normally closed through a second biased switch, a radio transmitter including an aerial circuit and a filament heating circuit, a plurality ofcontacts in said transmitter circuits adapted to be perma-' \nently connected to leads which terminate in a plug connection adapted to be insertedin corresponding sockets in said receiver and means onsaid plug connection for opening o.

the normally closed switch in said receiver aerial circuit on insertion of said plug in the receiving socket.

3. In radio apparatus to be used for duplex operation the combination of a receiver including an aerial circuit normally closed through a spring biased-. v contact, a radio transmitter including a thermionic oscillation repeater and an aerialcircuit, andzmeans for adaptingsaid apparatus to intercommunication including a manually operated in said transmitter adapted in one pcsition to render said oscillation repeater operative and to connect said transmitter aerial system, and in another position to render said oscillation repeater inoperative and to disconnect said transmitter aerial system, and means for connecting the transmitter aerial to said radio receiver when the manually operated switch is in the last position including a plug connector normally connected to contacts associated with said switch at one end and adapted to be plugged in to sockets in said receiver circuits at the other end.

4:. Apparatus as claimed in claim 3 in which said plug includes means for disconnecting said receiver aerial when said plug is inserted in the sockets in said receiver.

KARL HEFFNER. 

